It's a sign of the times that at the annual convention of the American Association of Petroleum Geologists, held in Houston recently, there were panels and keynote speakers devoted to worries about finding enough oil and gas for the world-and seeking ways for the U.S. to wean itself from crude oil altogether. Clearly, the subject of world oil supply and the timing of peak oil production is troubling the world's geologists. From 1995 to 2004, the world produced about 250 billion barrels of oil equivalent (BOE), yet discoveries during that period found only 150 billion, according to data from IHS Energy. Despite the anxiety these data may cause, global oil production actually increased, thanks to reserve adjustments and the application of new technologies in giant fields that were already found by 1996, according to Sandy Rushworth, now senior geologist with Marathon Oil. She was with IHS when the data were compiled. "This is an exploration dilemma, but growth in giant fields will meet demand," she said. As new knowledge about existing fields is gained through production history, their reserves typically grow greater. Reserves added within existing fields from 1995 to 2004 climbed by 457 million BOE-three times the rate of discoveries made during the period. Most of those increases came from giant fields. "There has been growth of 111% versus what we thought we had back in 1981. By 1996, some 150 more fields were reporting. And, we found 348 billion BOE from 1996 to 2005, in fields that had been discovered by 1996. Most of this was in the former Soviet Union and the Middle East." From 2004 to 2015, the challenge is that the world will need an additional 50 million barrels per day of supply, given current production decline rates, and an assumed moderate increase in world oil demand of 1.9% per year, she said. By 2015, non-traditional energy sources, such as the heavy oils in Canada and Venezuela, gas-to-liquids and liquefied natural gas, will make up 30% of total world supply, versus just 10% in 1990. The industry will meet world oil demand through 2015, she said. The giants that now make up only 3.5% of the world's fields harbor 78% of the reserves, and those reserves are growing through application of new technologies. Meanwhile, the U.S. has doubled its efficiency of oil use since 1975 and ought to do so again, said Amory Lovins, who manages the Rocky Mountain Institute in Snowmass, Colorado. "My idea is arrestingly simple. Over the next few decades, the U.S. can get off oil altogether, using technologies that existed as of 2004, and do so with companies making a profit," said Lovins. His 2004 book, Winning the Oil Endgame, gives details on how the U.S. can save oil and substitute oil by making changes to technology and making consumer habits more efficient. "Since 1975, some 78% of the increase in energy supply in the U.S. has been fueled by greater energy productivity or efficiency. Only 22% has come from an increase in the actual physical supply. The cost of saving energy is equivalent to buying gasoline for 57 cents per gallon." A profitable transition beyond oil is possible, he said, due to the use of light-weight composite or carbon-fiber materials for vehicles, as well as fuel-efficient homes and commercial and industrial buildings.